NIR-based prediction of extractives in American white oak heartwood

Abstract White oak is commonly used for cooperage and the heartwood extractives are important for this application because of their impact on the flavor and color of wine and spirits aged in white oak barrels. White oak extractives comprise a complex mixture of compounds and the composition of the mixture can change within trees over time. The ability to monitor the extractives component of white oak heartwood could be helpful for assessments of barrels and their contents. Wood from five American white oak stave logs was sampled. NIR-based models could provide reasonable predictions of the concentration of individual extractives components. However, these extractives were highly correlated to one another and to radial location suggesting that segregation of white oak material based on distance from the pith could be an efficient method for selecting samples that are relatively rich in flavor-associated chemicals. The relatively poor near infrared-based prediction ability for total extractives content could be due to age-related changes in the composition of the mixture of extractives across the radius.